| systemd-reboot.service(8) - phpMan
SYSTEMD-HALT.SERVICE(8) systemd-halt.service SYSTEMD-HALT.SERVICE(8)
NAME
systemd-halt.service, systemd-poweroff.service, systemd-reboot.service, systemd-
kexec.service, systemd-shutdown - System shutdown logic
SYNOPSIS
systemd-halt.service
systemd-poweroff.service
systemd-reboot.service
systemd-kexec.service
/lib/systemd/systemd-shutdown
DESCRIPTION
systemd-halt.service is a system service that is pulled in by halt.target and is
responsible for the actual system halt. Similarly, systemd-poweroff.service is pulled in
by poweroff.target, systemd-reboot.service by reboot.target and systemd-kexec.service by
kexec.target to execute the respective actions.
When these services are run, they ensure that PID 1 is replaced by the
/lib/systemd/systemd-shutdown tool which is then responsible for the actual shutdown.
Before shutting down, this binary will try to unmount all remaining file systems, disable
all remaining swap devices, detach all remaining storage devices and kill all remaining
processes.
It is necessary to have this code in a separate binary because otherwise rebooting after
an upgrade might be broken — the running PID 1 could still depend on libraries which are
not available any more, thus keeping the file system busy, which then cannot be re-mounted
read-only.
Immediately before executing the actual system halt/poweroff/reboot/kexec systemd-shutdown
will run all executables in /lib/systemd/system-shutdown/ and pass one arguments to them:
either "halt", "poweroff", "reboot" or "kexec", depending on the chosen action. All
executables in this directory are executed in parallel, and execution of the action is not
continued before all executables finished.
Note that systemd-halt.service (and the related units) should never be executed directly.
Instead, trigger system shutdown with a command such as "systemctl halt" or suchlike.
SEE ALSO
systemd(1), systemctl(1), systemd.special(7), reboot(2), systemd-suspend.service(8)
systemd 215 SYSTEMD-HALT.SERVICE(8)
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